This R01 is to request a five-year prevention services project to: 1) test the impact, through third grade, of a first-grade cLassroom-based intervention in 2 cohorts which are systematic replicates of a 1st cohort, 2) examine the variation in intervention impact to determine what works for which children under which conditions with a specific focus on the responders versus non-responders, and 3) strengthen the test of multi-level model for sustaining practices and going-to-scale. The Whole Day First Grade Program (WD) is directed at two correlated and confirmed early antecedents of drug abuse and other co-morbid disorders, early aggressive, disruptive behavior and poor achievement. WD focuses on teachers' classroom behavior management, family/classroom partnerships regarding homework and discipline, and teachers' instructional practices, particularly around reading. A randomized, epidemiologically-based, experimental design addresses, in parallel, an effectiveness trial of the Whole Day First Grade Program (WD) and a test of the utility of a multi-level support structure to sustain and disseminate WD, as the data warrant. Teachers and 1st graders within each of 12 schools were randomized to an intervention or standard program classroom. We have completed one year of an effectiveness trial with 1st graders in Cohort 1 (school year 2003-04) and are following this cohort to 3rd grade. We are also following the 1st grade teachers as they teach 2 subsequent cohorts of 1st graders to test whether the multi-level structure of training and support sustains high levels of WD practice and if it can be used to train non-WD teachers. This independent R01 requests funds to collect data on the 2 subsequent cohorts of 1st grade students, who will serve as systematic replicates of Cohort 1. Data will be collected in 1st grade and in spring of 3rd grade. We also seek to retain key intervention staff over Cohorts 2 and 3 to strengthen the multi-level model of program dissemination. The application builds upon current work to maximize efficiency of both costs and time in developing, replicating and extending to system-wide use evidence-based prevention programs.